What Codex Is Missing: It’s the Harness, Not the Model

What variant of Codex are you using?

App, IDE Extension

What feature would you like to see?

Hi Codex team,

First of all, great work — Codex is already extremely strong at the model level. In my experience using multiple systems side by side, the gap today is not the model capability, but the harness around it.

I wanted to share some structured feedback that might be useful for future improvements.

Context

In practice, I use Codex alongside other coding agents (e.g., Claude Code). From a pure model capability perspective, they feel very close. On difficult tasks, when one struggles, switching to the other usually resolves the problem.

Head-to-head, both are strong. The difference in day-to-day usage comes from the harness, not the model.

1. Planning and task visibility

One of the biggest usability improvements would be:

• Breaking complex tasks into explicit subtasks
• Maintaining a visible, persistent task list during execution
• Ensuring all items are completed before signaling "done"

This has a big impact on trust. When a system exposes its plan and progress clearly, it's much easier to verify completeness without repeatedly prompting for missed steps.

Concrete example from my workflow:

With other systems, when they say “done,” I can actually verify that every subtask was completed because the list is visible and tracked. This removes the need to double-check or ask follow-up questions like “what about that other item?”

This significantly improves confidence and reduces interaction overhead.

2. Parallel task execution / interruption handling

Another key area is how the system handles interruptions:

• If a task is running and the user asks something new, ideally:
• The current task continues when possible
• The new task starts in parallel
• If interruption is required, the system should be able to reliably resume previous work from where it left off

Right now, the workflow tends to be more serial:

• Interrupting a task often cancels it
• Resuming requires manual re-instruction

Concrete example from my workflow:

When I interrupt Codex to ask something else, the current task is usually stopped. To continue, I need to manually guide it back to the previous state.

In contrast, in systems that support parallel execution, I can:

• Start a new request
• Keep previous tasks running
• Manage multiple threads of work simultaneously

This allows a much more fluid workflow, where I can “open new fronts” without losing progress on existing ones.

With Codex, I tend to adapt my behavior:

• Smaller, more focused prompts
• One task at a time
• Waiting for completion before moving on

It works well, but it’s a more serial and less fluid interaction model.

Why this matters

From a user perspective, these two aspects (planning + parallelism) significantly affect:

• Trust in completion
• Ability to stay in flow
• Overall productivity

In my opinion, Codex is already very close to being best-in-class. Improving the harness in these areas could meaningfully close the remaining gap.

Final note

I understand from the contribution guidelines that core changes are internal, so I’m sharing this as product feedback rather than a code proposal.

Happy to expand on any of these points if useful.

Thanks again for the great work.

Additional information

_No response_